1. Field
The following description relates to a wireless access network, and more particularly, to technology for assuring quality of service (QoS) in consideration of fairness between users in a wireless access network.
2. Description of the Related Art
In a contention-based wireless access network, a plurality of terminals contend for access to a channel. IEEE 802.11 WLAN fundamentally uses the distributed coordination function (DCF) and the hybrid coordination function (HCF) in 802.11e.
IEEE 802.11 mandates wireless stations to check if the medium is idle for a given period of time—sum of the inter-frame space (IFS) and the contention window (CW)—by waiting with sensing the medium before transmitting packets. The HCF of IEEE 802.11e further provides the enhanced distributed channel access (EDCA) that specifies a set of arbitration inter-frame spaces (AIFS) and contention window boundaries to differentiate the channel access probability according to the priority of traffic streams. Basically, the smaller value of AIFS and CW for higher-priority traffic gives the higher chance of packets being sent.
Although such a channel access method provides a way of traffic prioritization in wireless access networks, the fair use of the medium among wireless terminals is not properly considered in the literature; for example, a greedy terminal may send high-priority traffic packets incessantly causing monopoly on the channel while other terminals in contention thus experience starvation.
U.S. Patent Publication No. 2010/0135264 discloses technology in which each of a plurality of terminals adjusts the use of an access channel according to a rate control algorithm.